Shuichi was friends with a boy named Tetsuya (and Tetsuya is literally the same as pregame Keebo in design), and Shuichi had developed feelings for Tetsuya, but never really realized he did until after an...unfortunate situation happened. Tetsuya got gravely sick one day and had to go to the hospital, but the nurse taking care of him...well, killed him. Shuichi figured out it was a murder, and that's how he became the ultimate detective. after like- 5 or 6 years, Keebo joins the school, and is literally the spitting image of Tetsuya, and Shuichi is ***very*** aware of this. Shu keeps seeing too many similarities to Tetsuya when he looks and interacts with Keebo. (btw there is very little connection to Keebo and Tetsuya. But Keebo was Built by Tetsuya's father, PROFESSER OLVIER), Shuichi wants to see Keebo as well, Keebo, but he just can't. He thought he got over his grief of losing his best friend, but he lied to himself, he thought he gained some self-confidence but again, he lied to himself. Keebo tries to help Shuichi and be his friend during all of this, and when they finally do become friends Shuichi breaks after 6 months. He reveals all of this to Keebo, and Keebo hugs Shu, telling him that he'll be okay. And later down the line, Shuichi starts to develop a crush on Keebo, but he's scared that it's just because of how Keebo reminds him of his first crush, and not about Keebo himself. Keebo helps Shu come to terms with Tetsuya's death and Shuichi finally decides to tell Keebo his feelings. Sadly some heartbreak happens, (Keebo had fallen in-love with someone else, who get to decide who, most likely it'd be best to make someone up-), and Shuichi falls back into his depressed shell. After some shenanigans, and Kokichi telling Keebo about Shuichi's state, Keebo breaks up with whatever character you chose. He finds Shuichi on the roof contemplating everything he's done. Keebo tries to calm Shuichi down, and fails. Then Keebo says: "I CARE ABOUT YOU DAMN IT! SO PLEASE JUST GET DOWN FROM THERE AND WE CAN TALK THIS OUT!"  Calming down Shu,  confessions take place, and then maybe a heated kiss or something of the sort-